WEDNESDAY, November 10 (Health.com) — The rapid-fire visual puzzles that make Tetris so engrossing may also make the video game a promising treatment for post-traumatic stress, a new study suggests.

Recurring, intrusive thoughts of a traumatic event (or events) are one of the hallmark symptoms of post-traumatic stress disorder (PTSD), a type of anxiety disorder. According to the study, which appears in the journal PLoS ONE, playing Tetris soon after a traumatic experience appears to protect against these flashbacks, by distracting the brain from the event and short-circuiting how upsetting memories and images are stored.

Not just any video game will do. Notably, the study found that games that rely on trivia or language skills don't appear to have the same therapeutic effect as stacking Tetris blocks, probably because they activate different areas of the brain.

"Verbal tasks may not be as effective because they will not affect the same neural networks," says Alexander Obolsky, MD, a professor of psychiatry at Northwestern University, in Evanston, Ill., who specializes in the treatment of PTSD. "It's a different part of the brain that processes that information." (Dr. Obolsky was not involved in the new research.)

To explore the effect of Tetris on post-traumatic stress, researchers in the U.K. used a well-known lab model of trauma: They showed a series of upsetting film clips (fatal car accidents, graphic surgery) to 60 people, then asked the participants to record how often they experienced flashbacks from the film.

The volunteers, who had no history of mental health problems, were divided into three groups. Shortly after watching the film, one group played Tetris, another played a word-based quiz computer game, and the third simply sat quietly.

In the first 10 minutes, the participants who played Tetris had just four flashbacks, on average. By comparison, the quiz-game players had about six flashbacks, and the participants who did nothing had 12 flashbacks.

More importantly, the protective effect of Tetris seemed to be lasting. Over the following week, members of the Tetris group continued to experience fewer flashbacks compared to the quiz-game and control groups. (The researchers asked the participants to record their flashbacks in a diary.) The group who played the quiz game actually experienced more flashbacks over the week than the group who did nothing.

"A visuospatial task such as Tetris may offer a 'cognitive vaccine' against the development of PTSD flashbacks after exposure to traumatic events," the researchers concluded. The study was led by Emily Holmes, a senior research fellow in psychiatry at Oxford University.

While the results of the experiment suggest a way to head off PTSD, much more research is needed before experts can start recommending Tetris or similar visual tasks for trauma victims in the real world.

"If this indeed keeps working in various situations in further studies, then perhaps at one point we can try it with people who have actual PTSD," Dr. Obolsky says. But, he adds, "there are years before this may or may not have something to do with what I do in my office with my patients."

Effective therapies that can be administered within hours of a traumatic event are desperately needed, Holmes and her colleagues write. In fact, they note, some existing forms of early-intervention counseling can even make PTSD symptoms worse.